There's a bit of a story going on between Google, Acer, and Alibaba, a Chinese mobile operating system vendor. Acer wanted to ship a device with Alibaba's operating system, but Google asked them not to, and Acer complied. The reason is that Acer is a member of the Open Handset Alliance, which prohibits the promotion of non-standard Android implementations - exactly what Alibaba is shipping. On top of that, Alibaba's application store hosts pirated Android applications, including ones from Google.

Google is saying that you can't use a non compatible Android fork. The Chineese company is saying its not a fork. It's Linux with an Android compatible runtime.

Except that the statement that it's not a fork is, for all we know, false. Google's Android chief Andy Rubin is quoted as stating this:

the Aliyun OS incorporates the Android runtime and was apparently derived from Android

Apparently they didn't re-implement a new VM, libs and tooling like Google did with Java. Instead they simply lifted portions of the Android OS wholesale. This would make Aliyun clearly a derivative work of Android and therefore a fork.